Scientific theory-a well-tested concept that explains a wide range of observation Plates-the lithosphere broken into separate sections Plate tectonics-a geological theory that states the pieces of Earth's lithosphere are in a constant, slow motion, driven by convection currents in the mantle Faults-breaks in Earth's crust where rocks have slipped past each other Divergent boundary-where two plates move apart, or diverge, usually occurs in the mid-ocean ridge Transform boundary-where two plates slip past each other, moving in opposite directions Rift valley-a deep valley that forms where two plates move apart Collisions-when two plates converge, it's called a collision, it may bring together oceanic crust and oceanic crust, oceanic crust and continental crust, or continental crust and continental crust
Outline:
A Theory of Plate Motion
the theory of plate tectonics explains the formation, movement, and subduction of Earth's plates
pieces of Earth's lithosphere are in slow motion
plates move by floating on the top of the asthenosphere
plates can do a lot:
collide,
pull apart
grind past each other
Plate Boundaries
three boundaries:
transform boundaries
crust is neither created nor destroyed
divergent boundaries
when divergent boundaries form on land, two of Earth's plates slide apart
convergent boundaries
when two plates collide, the density of the plates determines which one comes out on top
oceanic crust is more dense than continental crust
when two plates carrying continental crust collide, subduction does not take place
The Continents Slow Dance
Plates move at 2.5 centimeters per year (very slow)
these plates have been moving for tens of millions years
about 260 million years ago, the continents were joined together in the supercontinent that Wegener called Pangaea.
about 225 million years ago, the supercontinent broke apart.
Table of Contents
1.5 The Theory of Plate Tectonics
Vocabulary:
Scientific theory-a well-tested concept that explains a wide range of observation
Plates-the lithosphere broken into separate sections
Plate tectonics-a geological theory that states the pieces of Earth's lithosphere are in a constant, slow motion, driven by convection currents in the mantle
Faults-breaks in Earth's crust where rocks have slipped past each other
Divergent boundary-where two plates move apart, or diverge, usually occurs in the mid-ocean ridge
Transform boundary-where two plates slip past each other, moving in opposite directions
Rift valley-a deep valley that forms where two plates move apart
Collisions-when two plates converge, it's called a collision, it may bring together oceanic crust and oceanic crust, oceanic crust and continental crust, or continental crust and continental crust
Outline:
A Theory of Plate Motion
- the theory of plate tectonics explains the formation, movement, and subduction of Earth's plates
- pieces of Earth's lithosphere are in slow motion
- plates move by floating on the top of the asthenosphere
- plates can do a lot:
- collide,
- pull apart
- grind past each other
Plate Boundaries- three boundaries:
- transform boundaries
- crust is neither created nor destroyed
- divergent boundaries
- when divergent boundaries form on land, two of Earth's plates slide apart
- convergent boundaries
- when two plates collide, the density of the plates determines which one comes out on top
- oceanic crust is more dense than continental crust
- when two plates carrying continental crust collide, subduction does not take place
The Continents Slow Dance